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WSET 3 > Vinification > Flashcards

Vinification Flashcards

1
Q

EU definition of “wine”

A

The product obtained exclusively from the total or partial alcoholic fermentation of fresh grapes, whether or not crushed, or of grape must

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2
Q

Grape maturity

A

One of the most decisive factors in determining wine quality and style Physiological changes - phenolics & taste Biochemical changes - sugars & acids

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3
Q

Key questions for harvesting

A

When

Forecasting

Preparing

How (manual vs machine)

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4
Q

Harvest date

A

Grape ripeness

  • sugar
  • acid
  • health
  • phenolic ripeness

Agrochemicals (fungicides, insecticides, herbicides, pesticides, etc)

  • withholding period
  • fermentation and health problems

e.g. sulphur –> hydrogen sulphide

copper –> brown haze, toxic copper salts in wine

Weather

  • rain –> dilution, grape swelling and bursting
  • hail

Availability of resources (human and mechanical)

Legal restrictions

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5
Q

Havesting - Getting ready

A

Estimating the crop (sufficient tank space)

Checking & cleaning equipment and machinery

Tanks clean and ready for use

Oenological products (yeasts, sulphur, enzymes, etc)

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6
Q

Havesting - Machine vs Hand

A

Factors to consider

  • quality
  • speed
  • economics
  • feasibility

Machine

  • speed, grapes at peak; cheaper labour costs; cool night
  • damage, oxidation, no selection, cost of machinery, flat land, trellis system (no bush nor pergolas)

Manual

  • less damage, more selectivity, slopes, less $ for equipment
  • high labour costs (10X machine), slower
  • for sparkling wine, carbonic maceration (whole bunches); Tokaji, Beerenauslese, Trockenbeerenauslese (selection of grapes); required by law
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7
Q

Harvesting - Transport & Reception

A

Use shallow picking containers

Less transfer between containers

Less dumping heights

Refrigerated trucks

Minimize delay before processing

Oxidation

  • browning, loss of aroma
  • CO2/nitrogen blanket; potassium metabisulphite; harvest at night; min delay

Microbial growth

  • eliminate rotten grapes; clean equipment; berry integrity; min delay

Contamination

  • rain
  • leaves & stalks
  • MOG (material other than grape)
  • soil
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8
Q

Key questions for grape processing

A

Sorting

De-stemming

Crushing

Type of press

Amount of SO2

Must treatments

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9
Q

Sorting in French

A

Triage

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10
Q

De-stemming

A

Tannin control and ease of processing

Egrappoir = de-stemming machine

Most grapes are de-stemmed

Not for sparkling wines and carbonic maceration

Not required for machine harvested grapes

Pros

  • prevent release of phenolics, herbaceous flavours, MOG
  • more efficient pressing
  • remove water and potassium (absorb colour and alcohol)

Cons

  • whites: slower pressing and drainage (not for fine wines)
  • reds: compaction of pomace cap; tannins and colour
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11
Q

Crushing

A

Release free-run juice

Reduce the solid parts of the grape to the correct condition for fermentation and maceration Increase extraction of tannin and colour

Careful not to damage grape seeds

Not to crush for semi-carbonic maceration (Spain, Beaujolais, Languedoc-Roussillon for Carignan and Grenache)

Fouloir = crusher

Equipment

  • foot or de-stem/crush
  • heat exchanger
  • SO2 to reduce oxidation and prevent microbial spoilage
  • use of pectolytic enzymes to release more juice
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12
Q

Pressing

A

Use of minimum pressure

Done at grape reception for whites; after fermentation for reds

70% of the total weight

Skin contact for aromatic whites (Sauvignon Blanc, Semillon, Muscat, Riesling, Gewuztraminer, Viognier)

  • 5-10 C
  • few to 24 hours -
  • pectolytic enzyme

Finest aromatic wines

  • very gentle whole-bunch pressing
  • no skin contact
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13
Q

Types of press

A

Vertical screw press (basket press)

  • simple and easy; clear must or wine
  • slow, labour intensive; extraction of bitter phenolics; oxidation
  • high-class wineries; champagne

Horizontal screw press (e.g. Vaslin)

  • more efficeint in terms of time and labour; simple; can be automated; prevent oxidation with inert gases
  • rather coarse juice; extraction of bitter phenolics; high pressure reduces quality

Pneumatic press (e.v. Willmes)

  • low pressure; good extraction; less bitter phenolics; high quality juice
  • very slow

Tank press (pneumatic press with inert gas)

  • no oxygen contact; high quality juice
  • very slow; costly

Continuous screw press

  • high throughput; less labour-intensive and time consuming
  • poor quality; bitter phenolics
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14
Q

Must Treatments

A

Before fermentation

  • SO2
  • Clarification
  • Enrichment or Chaptalisation
  • Must concentration
  • De-acidification
  • Acidification
  • Tannin
  • Bentonite
  • Flavour and colour enhancing enzymes
  • Oxygen
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15
Q

SO2 in winemaking

A

Prevent oxidation and premature fermentation

Kill bacteria (for whites)

Stun weaker yeasts

Improve extraction of polyphenols from skins (for reds)

Four properties:

  • Antiseptic - kills microorganisms (acetobacter/wild yeasts)
  • Antioxidant - binds with oxygen
  • Antioxidasic - denatures oxidasic enzymes
  • Combines with acetaldehyde (by-product of oxidation)
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16
Q

Four forms of SO2

A

Potassium metabisulphate powder

Compressed and liquidified SO2 gas

SO2 in solution (5%)

Burning sulphur tablets or candles

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17
Q

SO2 levels

A

Based on style of wine, health of grapes, pH

Lower for organic wines

Recommended

  • White: 60-100 mg/l
  • Red: 10-60 mg/l

Limits -

  • Dry white: 200 mg/l
  • Dry red: 150 mg/l (red wines contain natural anti-oxidants)
  • Off-dry white (5g/l sugar): 250 mg/l
  • BA/TBA/Sauternes: 390 mg/l (binding power of sugars)
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18
Q

Free, bound and total SO2

A

Free - active, protective, molecular SO2 & sulphurous acid

Bound - combined with sugars, aldehydes, ketones, inactive

Total - free + bound

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19
Q

Pre-fermentation clarification

A

Remove solid particles

Produce cleaner flavours, more finesse, less bitter

Depend on

  • state of the harvest
  • grape processing method
  • wine style required (little for full-bodied, complex wines; more for delicate and highly aromatic wines)
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20
Q

Clarification methods

A

Cold settling (common)

  • debourbage
  • by gravity
  • 12 to 24 hours
  • cool temperature (5-10 C)
  • clear must racked off the sediment (lees)
  • pectolytic enzymes and SO2

Centrifugation

  • high level of clarity
  • harsh, high risk of oxidation, expensive
  • large wineries

Diatomaceous earth filtration

  • for aromatic grapes
  • can strip the must of nutrients for fermentation

Flotation

  • bubbling small amounts of N, CO2 or air
  • catching and floating solid particles
  • skimmed off by a rotary suction device
  • large wineries or cooperatives
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21
Q

Enrichment

A

Adding sugar to increase potential alcohol

No effect on wine sweetness

Permitted in cool regions

Unusually cool summer or early harvest in warm regions

Not allowed in Italy/Spain

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22
Q

Forms of sugar for enrichment

A

Sucrose (beet sugar) or cane sugar - chaptalisation

RCGM (rectified concentrated grape must) - enrichment

1 kg of sugar increase vol of wine by 0.63 l

White: 1% abv require 17 g/l sugar

Red: 1% abv require 19 g/l sugar (evaporation due to higher fermentation temp & pumping over)

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23
Q

Must concentration techniques

A

Vacuum evaporation

  • water evaporates at low temperature of 20 C
  • loss of aromas, hence use of chilled aroma trap

Reverse osmosis

  • high pressure applied to must against a membrane filter
  • no loss of aromas
  • also used to remove alcohol and volatile acidity

Cryoextraction

  • chill grapes to remove water in from of ice
  • no loss of aromas
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24
Q

EU Rules on enrichment

A

Wine must be > 8.5% alcohol

Enriched wine < 11.5% (white) or 12% (red and rose)

Concentration not to increase alcohol by > 2% or reduce vol by 20% (whichever is lower)

Only one enrichment method and no blending of differently enriched wines

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25
Q

Potential alcohol

A

Alcohol level that would result if all sugars are fermented

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26
Q

Actual alcohol

A

Actual alcohol level after fermentation

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27
Q

Residual sugar

A

Unfermented sugars (natural or added) left in the wine expressed as g/l or %

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28
Q

Total alcohol

A

Actual alcohol + potential alcohol from residual sugar

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29
Q

Natural alcohol

A

Total alcohol in an un-enriched must or wine

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30
Q

De-acidification

A

Tartaric acid cannot be reduced by > 1 g/l

Not permitted in warmest regions - CIII(b)

Increase pH, therefore risk of microbial infection and decrease effectiveness of SO2

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31
Q

De-acidification methods

A

Tartaric only

  • potassium bicarbonate (potassium tartrate crystals)
  • calcium carbonate (leaves high level of calcium tartrate)

Malic only

  • malolactic fermentation

Both tartaric and malic

  • Double-salt de-acidification
  • Acidex (specifially prepared calcium carbonate with small amount of calcium tartrate-malate)
  • calcium tartrate-malate crystals
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32
Q

Acidification

A

“buffering” effects

logorithmic pH scale

  • more acid to alter pH from 3.2 to 3.0 than from 3.8 to 3.6

CII and CIII zones

Not in Rhone

Tartaric acid for acidification

  • 1.5 g/l in must; 2.5 g/l in wine

Citric acid

  • 1 g/l in must
  • never added before fermentation
  • metabolised by yeast and bacteria to form acetic acid
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33
Q

Tannin

A

Added before fermentation

Protection from oxidation

Stablilize colour

Improve mouth feel

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34
Q

Bentonite

A

Fining agent in form of clay

Remove proteins

Non-selective and remove flavour compounds

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35
Q

Flavour and colour enhancing enzymes

A

Aid juice extraction

Optimise extraction of aroma precursors

Improve colour extraction

Increase efficiency of settling

Developed from fungi

Added at crushing

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36
Q

Use of oxygen in winemaking

A

Hyperoxidation

Development of yeasts at start of fermentation

Revitalization of yeast

Micro-oxygenation of harsh polyphenols in barrels

Anaerobic maturation after bottling (not for screwcaps)

Add complexity and character in anaerobically made wines

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37
Q

Oxidases

A

Laccase

  • grey rot
  • SO2 resistant
  • pasteurisation (heating must to 65-70 C)

Tyrosinase

  • controlled by SO2 Copper and iron
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38
Q

Reductive (anaerobic) handling

A

Minimize exposure to oxygen

SO2

Low temperatures

Inert gases used to flush out presses, pipes, vats

Reductive taint - sulphur dioxide becomes hydrogen sulphide

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39
Q

Oxidative (Aerobic) handling

A

Minimal use of SO2

Controlled exposure to oxygen

Develop complex flavours and aromas

Enzymatic oxidation of phenolics is encouraged

Form insoluble polymers removed by clarification

More stable wine

Production of oloroso Sherry, tawny Port, vin jaune from the Jura, some Tokaji

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40
Q

Hyperoxidation

A

Bubbling air through the juice

Colour stabilisation in white wines

Can decrease aromalics (e.g. Sauvignon Blanc)

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41
Q

Effects of excessive oxygen

A

Acetaldehyde (ethanal) –> flat sherry-like flavour

Bitter-tasting components from oxidation of phenolics

Spoilage bacteria, e.g. acetic bacteria

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42
Q

Ascorbic acid

A

Vitamin C

Antioxidant

No antiseptic effect

Used without SO2 –> hydrogen peroxide (bleaching agent)

43
Q

Alcoholic fermentation

A

Glucose/fructose + yeasts –> ethanol + CO2 + energy

  • 180 g sugar –> 92 g alcohol + 88 g CO2

Saccharomyces yeast

  • 16-18 g/l sugar needed to produce 1% abv (8 g/l)

Glucose

  • dominant early in ripening process
  • yeast prefer glucose

Frutose

  • dominant in very ripe grapes
  • late harvest or botrytis-affected grapes
  • difficult to ferment fructose-rich grape must to dry wine
44
Q

Rate of fermentation

A

Concentration of sugars

Availability of oxygen

Temperature

Type and quantity of yeasts

Nutrient content of the must

SO2

45
Q

Fermentation ceases

A

All sugar consumed

Alcohol reaches 15% killing yeasts

Increasing pressure of CO2 to 7 atmospheres

Chilling to low temperature (5 C)

SO2

Pasteurisation (80 C for a few second)

Removing yeasts (filtration, centrifuge)

Fortification with spirit

46
Q

By-products of fermentation

A

Glycerol (Glycerine) - smoothness and weight of wine

Acetaldehyde

Ethyl acetate (nail polish)

Aroma esters

Fusel oils, e.g. methanol

47
Q

Fermentation vessels

A

Stainless steel tanks

  • easy to clean and maintain
  • allow temperature control
  • rotofermenters

Wooden fermentation vessels

  • piece (228 liters) in Burgundy
  • barrique (225 litres) in Bordeaux, New World
  • open top wooden vats - 1000-5000 litres
  • wood retains heat well, need temp control
  • difficult to keep clean
  • chestnut, cherry, acacia & walnut

Cement tanks

  • lined with glass or epoxy
  • cheap
  • easy to clean and maintain
  • no oxygen exchange
  • simple temp control
48
Q

Uninoculated fermentations

A

Started by indigenous yeasts

  • Kloeckera/Hanseniaspora
  • Candida
  • Metschnikowia

Around 4% alcohol

  • Saccharomyces takes over
  • Saccharomyces cerevisiae

Pros: complex wine

Cons: off-flavours, oxidation, microbiological spoilage

Pied de curve - starter culture

49
Q

Inoculated fermentation

A

Commercially available active dry yeast

  • different strains of Saccharomyces cerevisiae
  • higher tolerance of SO2

Pros

  • active fermentation onset
  • handle highly clarified juice
  • fermentation rate more even and easy to control
  • no off-flavours or aromas
  • efficient conversion of sugar to alcohol
  • decreased risk of stuck fermentations
  • low volatile acidity (acetic acid) production

Attributes

  • tolerance to higher sugar levels (Lalvin Rhone 2226)
  • higher glycerol production levels (Maurivin Cru-Blanc)
  • efficent extraction of phenolics and enhancement of tannin structure for high quality reds (Lalvin Rhone 2323)
  • low temperature tolerant for very fruity whites (R2)
  • low foaming (champagne yeasts, e.g. Premier Cuvee for secondary fermentation in bottle)
  • Sauvignon Blanc yeasts for aroma/thiol fixing (Lalvin K1V-1116)
50
Q

Monitoring and controlling fermentation

A

Density

  • measures sugar (not alcohol)
  • Baume (France): relative density
  • Brix or Balling (Australia, NZ, US): hydrometer measurement
  • Oechsle (Germany, Switzerland): hydrometer scale
  • Babo (Italy), same as KMW (Austria)

Temperature

  • controls the rate of fermentation
  • chill white grapes/must in warm climates
  • fermentation releases heat

Aeration

  • yeast needs oxygen
  • reds: pumping over (remontage) or punching down (pigeage)

Finishing the fermentation

  • density drops below 1
  • 2 g/l of unfermentable sugars in dry wines
51
Q

Temperature in fermentation

A

Optimum fermentation temperature range

  • whites: 10 - 18 C
  • reds: 20 - 32 C

Excessively high temperature

  • oxidation, microbiological spoilage and instability
  • loss of aroma and flavour compounds, alcohol
  • slow or stuck fermentation (above 35 - 38 C)

Excessively low temperature

  • retention of isoamyl acetate (banana/pear) in whites
  • poor extraction of colour and tannins in reds - sluggish fermentation
  • high levels of ethyl acetate and volatile aroma
52
Q

Options for finishing the fermentation

A

Aromatic dry white wines

  • chill the new wine
  • add SO2 (40-100 mg/l)
  • remove lees (settling or fining agent)
  • rack clean wine and bottle

Full-bodied Chardonnay

  • fermented in oak barrels
  • extended lees contact, with lees stirring
  • MLF
  • after MLF, suphited and left to mature in oak

Off-dry white wines

  • stop fermentation before dryness
  • chilled (< 5 C)
  • racked and filtered to remove yeasts

Sweet fortified wines (Port/vins doux naturels)

  • add alcohol to > 15% abv

Red wines

  • maceration to extract tannins and pigments
  • New World: fermentation completed in barrels, then MLF
53
Q

Fermentation problems

A

Stuck fermentations

Yeast nutrient issues

Hydrogen sulphide formation

Carbon dioxide poisoning

54
Q

Stuck fermentation results

A

Results in

  • hydrogen sulphide (VA)
  • microbial spoilage
  • residual sugar

Caused by

  • too hot (> 35 C) or too cold
  • nutrients depleted
  • alcohol level (uninoculated fermentation)

Prevented by

  • adequate aeration at onset of fermentation
  • 100 - 150 mg/l di-ammonium phosphate (DAP)
  • 0.5 mg/l thiamine (vitamin B)
  • temperature control

“kick-start”

  • adjust temperature
  • add DAP and thiamine
  • re-inoculate with Saccharomyces Bayanus
55
Q

Yeast nutrient issues

A

Low yeast nutrients in rotten fruit and clarifed must

Add DAP (200 mg/l) and thiamine (1.0 mg/l)

Ammonium sulphate liberates ammonium and SO2

56
Q

Hydrogen sulphide formation

A

Yeasts deprived of nitrogren (ammmonium)

Break down amino acids to release H2S

Rotten eggs

57
Q

Carbon dioxide poisoning

A

Colourless, odourless, potentially lethal

Heavier than oxygen

Good ventilation required

Measure oxygen using a meter

58
Q

White winemaking

A

Grapes pressed before fermentation

Good quality whites

  • healthy, ripe grapes
  • careful and quick processing
  • protection from oxidation

Key decisions

  • whole bunch press or de-stem and crush before pressing
  • de-acidify, acidify, increase sugar levels
  • skin contact (maceration pelliculaire) or press immediately
  • clarify must before fermentation
  • inoculate
  • fermentation vessel
  • fermentation temperature (14 - 20 C)
  • lees contact
  • MLF (No SO2, 16 - 18 C)
  • oak
  • maturation prior to bottling
59
Q

Fermentation temperature for whites

A

Optimum 14 - 20 C

  • fruit preservation
  • > 20 C reduce esters and increase alcohol

Aromatic whites

  • 11 - 15 C to retain fruit esters
  • 10 - 13 C to retain volatile esters but produce intense smelling esters (isoamyl acetate)

After fermentation, lower temp to 12 C for yeast settling

60
Q

Lees contact

A

Protect wine from oxidation

Add texture

Autolysis of yeast in lees

Muscadet

Reduction problems

  • H2S –> onion-like mercaptans, difficult to remove
  • oxygen by lees stirring or wine racking
  • pass through copper pipe or add copper sulphate

Lees stirring (battonage)

  • wine in barrique (Chardonnay)
  • barrel stackers with rollers to avoid excess oxygen
  • bubbling gas in tank
61
Q

Rose winemaking

A

Drawing-off method

  • saignee or bleeding
  • de-stemmed, crushed and sulphited grapes
  • 6 - 48 hours of skin contact
  • cooler temp to retain fruit aromatics and freshness
  • higher temp for more colouring
  • fermented at 15 - 20 C
  • no MLF to retain fresh natural acidity
  • clarified, stabilised and bottled young
  • Anjou, Bordeaux Clairet, Cotes de Provence

Direct pressing

  • freshly harvested red grapes
  • not to extract too much tannin
  • pale pink
  • Cotes de Provence, Languedoc

Blending

  • Rose Champagne, New World Roses
  • not permitted in EU for still roses
62
Q

Definition of “red wine”

A

A macerated wine.

Extraction of solids from grape cluster (specifically from skins, seeds and possibly stems) accompanies the alcoholic fermentation of the juice.

63
Q

Red winemaking

A

Skin contact during the alcohol phase and colour of the grape; extraction of phenolic compounds (polyphenolics or polyphenols); pressing after fermentation

5 main steps

  • pre-fermentation processing
  • alcoholic fermentation
  • draining and pressing
  • MLF
  • maturation
64
Q

Two main types of phenolic compounds

A

Non-flavonoids

  • simple phenolics
  • benzoic and cinnamic acids

Flavonoids

  • catechins (tannin)
  • resveratrol
  • anthocyanins (red pigments in skin cells)
  • tannin can react with anthocyanins to fix colour
  • pigmented tannins polymerise with age and precipitate out
65
Q

Three factors of phenolic extraction

A

Temperature of fermentation

DAP management

Duration of skin contact

66
Q

Pre-fermentation processing

A

De-stemming and crushing (not for carbonic maceration)

Fill vessel to < 80% capacity 20 - 80 mg/l SO2 (wild yeasts, bacteria, oxidative enzymes)

Must adjustment (acidification, enrichment)

Pre-ferment maceration (or “cold soak”) to extract aromas

  • Cooled to 4 - 15 C and kept for 3 - 7 days (80-100 mg/l SO2)
67
Q

Fermentation temperature for reds

A

20 - 32 C

Higher temp increase breakdown of skin cells and level of dissolution of phenolics

Moderate temp (25 C)

  • good colour extraction
  • preservation of primary fruit aromas
  • minimal to moderate tannin extraction

Thermovinification

  • heating grape to 45 C
  • rather coarse wines with “burnt” aromas
68
Q

Cap management

A

Pomace cap

Methods

  • pumping-over (remontage)
  • punching down (pigeage)
  • rackand return (delestage)
  • submerged cap
  • rotovinification
  • autovinification
69
Q

Pumping-over

A

Remontage

with or without aeration

pump, hose, fixed spray head

done 1-3 times a day

Benefits

  • simple
  • good extraction
  • tank of wine becomes homogenised
  • aeration prevents reduction, aids yeasts
  • prevents cap from drying out

Wines

  • Cabernet Sauvignon, Merlot
  • medium to high quality
  • rich, full-bodied structure
  • no vegetal or bitter characters
70
Q

Punching down

A

Pigeage

Manual (paddle)

Automatic (stainless steel cone attached to a hydraulic piston)

Done 1-3 times a day

Benefits

  • gentle extraction
  • less harsh or bitter compounds
  • good disperson of temperature
  • avoid bacterial spoilage on surface of cap

Disadvantages

  • labour intensive if done manually
  • Merlot and Cabernet Sauvignon more rustic in flavour

Wines

  • Pinot Noir and premium Syrah
71
Q

Rack and return

A

Delestage

Tank is drained into another tank, then pumped back over the cap

Done once per day or twice during fermentation

  • after initial peak of temp
  • middle of fermentation

Benefits

  • complete mixing and breaking up of cap
  • good aeration
  • extraction of phenolics
  • seeds can be removed

Disadvantages

  • too extractive
72
Q

Submerged cap method

A

Fermenting fluid filled to over head boards/perforated screen that trap pomace beneath

Constant contact

Benefits

  • good extraction
  • no risk of pomace cap drying out and VA

Disadvantages

  • extraction can be difficult as skins are compressed
73
Q

Rotovinification

A

Rotofermenter

  • horizontal cylindrical fermentation vessel
  • motor

Benefits

  • fast
  • thorough mixing
  • good extraction
  • automatic and computer-controlled
  • pomace kept wet

Disadvantages

  • expensive
  • robust supporting framework
  • reduction problems
  • over extraction

Wines

  • inexpensive, bulk reds
  • premium Barolo
74
Q

Autovinification

A

Autovinifier, or Algerian Ducellier system

  • extended version of pumping-over
  • sealed vats
  • CO2 pumps must into top reservoir
  • cascades back into lower chamber

Benefits

  • no external power
  • fully automated
  • good extraction of colour and tannins

Disadvantages

  • difficult to control rate of extraction

Wines

  • red Port
  • light, good quality wine in North Africa
75
Q

Fermentation management of reds

A

Complexity of maceration dynamics

Monitor density and temp

Control of temp

Control of aeration

Pumpovers and/or cap punching

Skin contact time (post-ferementation maceration)

76
Q

Duration of skin contact

A

Extraction enhanced by

  • higher temp
  • increase in alcohol

Extent of phenolic extraction

  • avoid extraction from poor quality grapes
  • shorter (around 8 days) for light, easy, early-drinking reds
  • longer (3 weeks) for full-bodied reds
  • extended (> 1 months) for high quality vintages

Pectolytic enzymes to increase extraction

Anthocyannis extracted first (temp)

Tannin extracted by higher temp and alcohol

77
Q

Draining and pressing

A

Free-run wine and press wine

Fining of press wine

Residual sugar in press wine to ferment out

78
Q

Maturation

A

Lees contact

  • reducing properties
  • fuller, smoother wines
  • mannoproteins released by lees autolysis
  • inhibit tartrate crystalization
  • bind with tannins to reduce astringency
79
Q

Malolactic fermentation (MLF)

A

Conversion of malic acid in a wine to lactic acid through the action of naturally-occurring or added bacteria

3 species of lactic acid bacteria

  • Lactobacillus
  • Leuconostoc
  • Pediococcus

Traditionally in tank

Today, commonly in barrel for better oak integration

Biologically more stable wine

Softer, rounder acidity

  • malic is sharp (unripe apples)
  • lactic is softer (milk)

By-products

  • diacetyl (buttery richness)
  • higher VA
80
Q

Conditions for MLF

A

pH between 3.3 - 3.5

Temp between 18 - 25 C

< 50 mg/l total SO2

Certain amount of nutrients

81
Q

Preventing MLF

A

Clarify (remove nutrients and bacteria)

SO2 addition after primary fermentation

Low storage temp (< 12 C) pH below 3.1

Clean containers

Sterile filtration & bottling

82
Q

Encouraging MLF

A

Keep wine in lees

Low levels of SO2

Warm temp (18 - 22 C)

pH above 3.3

Add Leuconostoc oenos (freeze-dried)

83
Q

Monitoring MLF

A

CO2

Reduction of malic acid

Paper chromatography

Enzymatic analysis

84
Q

Effects of MLF

A

Deacidification

  • cool climates
  • incomplete ripening

Stability

  • consuming bacteria nutrients
  • useful in reds as lack of protection of added SO2

Loss of primary fruit aromas

  • detrimental to aromatic whites

Addition of aromatic compounds e.g. diacetyl

  • spoil fruit aromas of Riesling or Sauvignon Blanc

Increase VA

  • breakdownof citric acid

Spoilage if lactic acid bacteria not controlled

  • SO2, low pH, equipment hygiene

Should never occur in the bottle

85
Q

Carbonic maceration

A

Fermentation within berries; no yeast; anaerobic respiration of grapes converts sugars to ethanol

Whole bunch

Blanket with CO2

Intercellular fermentation

2% abv and aromatic compounds

Decrease in malic acid, increase in pH

1-3 weeks

Aromas of bananas, kirsch, cherry, plum

86
Q

Semi-carbonic maceration

A

Beaujolais

Comibination of extra- and intracellular fermentation

No CO2 blanket

Vat filled with grape bunches

Fermentation of crushed bunches at bottom release CO2

Intercellular fermentation of upper layer bunches

Deeply coloured, fruity wines with soft tannins

87
Q

Thermovinification

A

Heat to 60 - 80 C for 20 - 30 minutes then cool to fermentation temp

Max colour extraction

“Time saver”

Destroy damaging oxidative enzymes in rotten grapes

Pectolytic enzymes and aromas destroyed

Not for premium reds

88
Q

Flash expansion

A

Flash detente

Pre-heat grapes to 65 - 90 C and place in vacuum

Grapes cooled immediately to 30 - 35 C

Rapid release of anthocyanins and tannins

Juice drained off

89
Q

Sparkling winemaking

A

Bottle fermented

Traditional Method (methode champenoise)

Transfer Method

Tank Method (cuve close or Charmat)

Carbonation (Pompe bicyclette)

Asti Method & Methode Ancestrale

90
Q

Fortified Winemaking

A

Types

  • Port, Sherry, Madeira
  • Muscat in Australia, S France, Greece, Italy
  • Vin de Constance (S Africa)
  • Malaga (S Spain)
  • Mavrodaphne (Greece)
  • Commandaria (Cyprus)

Methods

  • fortified during fermentation
  • fortified after fermentation
91
Q

Fortification during fermentation

A

Vins doux naturels

  • Muscat, Grenache (S France)
  • at 5% abv, add high-strength grape spirit (95% abv)
  • 15 - 18% abv

Port

  • maceration in granite troughts (lagares)
  • fermentation at high temp (> 30 C)
  • drain wine at 6 - 9% abv
  • 1 part of spirit (77 - 79% abv) to 4 parts of wine
  • 8 - 19% abv

Maturation -

  • 550 litre “pipe”

Port quality

  • base wine
  • single vintage or blend
  • time in cask - filtered?

Styles

  • Ruby Port (< 3 yrs)
  • Tawny Port (longer oxidative time)
  • Late Bottled Vintage Port (4-6 yrs)
  • Vintage (2-3 yrs)
92
Q

Fortification after fermentation

A

Sherry

  • Town of Jerez
  • Palamino, Pedro Ximenez
  • 70% free run for Finos, next 20% for Oloroso
  • acidified with tartaric acid
  • 600 litre oak butts
  • uninoculated fermentation (25 - 30 C)
  • dry wine, low in alcohol (11 - 11.5%)
  • Finos/flor (14.5 - 15.5%) (biologically aged)
  • Oloroso (18%) (oxidatively aged)
  • Amontillado (aged both biologically an oxidatively)
93
Q

Solera system

A

Criadera (row)

  • simple solera: 3 - 4 criaderas
  • complex solera: 14 criaderas
  • bottom row called Solera

Fractional blending

  • no more than 1/3 of contents drawn
  • complex wines
  • replenish nutrients for flor

Finos: 3 - 5 yrs

Amontillados/Olorosos: 5-10 yrs

Sweetened prior to bottling

  • Pedro Ximenez (Cream Sherries and Sweet Orlorosos)
  • concentrated grape juice (Pale Cream Sherries)

Membrane-filtered for Finos and Manzanilla (salty)

94
Q

Sweet wines

A

3 main methods

  • interrupting the fermentation
  • adding a sweet component
  • concentrating the natural sugars
95
Q

Interrupting the fermentation

A

Fortification

  • Vins doux naturels e.g. Muscat de Beaumes de Venise
  • Moscatel de Valencia
  • Liqueur Muscats e.g. Rutherglen Muscat

Add SO2 and lower temp

96
Q

Adding a sweetening component

A

RCGM

Sussreserve (unfermented grape juice)

  • German QbA wines
  • Rheingau, Rheinhessen, Mosel
97
Q

Concentration of sugars

A

Drying, e.g. on straw mats

  • passerillage -
  • Amarone, Vin Santo (Italy, Santorini), PX Sherry (Spain)

Freezing

  • Icewine/Eiswein Noble rot
  • botrytis cinerea -
  • Riesling, Semillon, Chenin Blanc
  • Sauternes, Monbazillac in France; Tokaji in Hungary; Beerenauslese and Trokenbeerenauslese in Germany and Austria; botrytis Semillon in Australia
98
Q

Sparkling winemaking

  • Traditional Method (methode champenoise)
A

Bottle fermented

Traditional Method (methode champenoise)

  • produce dry base wine
  • no SO2 added at end of fermentation
  • add liqueur de tirage and yeast
  • bottled and sealed (cork or crown seal) - secondary fermentation to increase 1.2 - 1.3% abv
  • autolysis of yeasts to add complexity -
  • riddled by hand or automatic ridding machines (remuage)
  • disgorgement
  • add liqueur d’expedition
  • sealed by cork and wire cage (muselet)
  • further aging
  • packing and distribution
  • Champagne, Cava, premium sparkling wines
  • complex wines, bready, biscuit flavours
99
Q

Sparkling winemaking

  • Transfer Method
A

Bottle fermented

Transfer Method

  • fermented wine emptied into pressurized tank
  • cooled to -5 C
  • add dosage (sweetening wine)
  • filter to bottle
  • slight loss of quality
  • mid-market New World sparkling wines
100
Q

Sparkling winemaking

  • Tank Method
A

Bottle fermented

Tank Method (cuve close or Charmat)

  • secondary fermentation in sealed pressurised tank
  • lees contact
  • sweetened, filtered and bottled under pressure
  • lower production costs
  • German Sekt and Prosecco
  • coarser and broader bubbles
101
Q

Sparkling winemaking

  • Carbonation
A

Bottle fermented

Carbonation (Pompe bicyclette)

  • chill wine
  • bubble carbon dioxide into it
  • very inferior method
102
Q

Sparkling winemaking

  • Asti Method
A

Bottle fermented

Asti Method & Methode Ancestrale

  • Moscato
  • must pumped into a pressure vessel and yeast added
  • CO2 allowed to escape to atmosphere
  • 5% abv: valves closed to trap CO2
  • 6-9% abv and 60-100 g/l sugar: cooled to 0 C
  • clarified, filtered and bottled
103
Q

Sparkling winemaking

A

Bottle fermented

Traditional Method (methode champenoise)

  • produce dry base wine
  • no SO2 added at end of fermentation
  • add liqueur de tirage and yeast
  • bottled and sealed (cork or crown seal)
  • secondary fermentation to increase 1.2 - 1.3% abv
  • autolysis of yeasts to add complexity
  • riddled by hand or automatic ridding machines (remuage)
  • disgorgement
  • add liqueur d’expedition
  • sealed by cork and wire cage (muselet)
  • further aging
  • packing and distribution
  • Champagne, Cava, premium sparkling wines
  • complex wines, bready, biscuit flavours

Transfer Method

  • fermented wine emptied into pressurized tank
  • cooled to -5 C
  • add dosage (sweetening wine)
  • filter to bottle
  • slight loss of quality
  • mid-market New World sparkling wines

Tank Method (cuve close or Charmat)

  • secondary fermentation in sealed pressurised tank
  • lees contact
  • sweetened, filtered and bottled under pressure
  • lower production costs
  • German Sekt and Prosecco
  • coarser and broader bubbles

Carbonation (Pompe bicyclette)

  • chill wine
  • bubble carbon dioxide into it
  • very infereior method

Asti Method & Methode Ancestrale

  • Moscato
  • must pumped into a pressure vessel and yeast added
  • CO2 allowed to escape to atmosphere
  • 5% abv: valves closed to trap CO2
  • 6-9% abv and 60-100 g/l sugar: cooled to 0 C
  • clarified, filtered and bottled

WSET 3 (2 decks)

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